During the operation of open-end spinning machines, it frequently occurs that very rapidly rotating rotors leave the position intended for them. Thus, it can occur that a rotor moves back and forth in the direction of the longitudinal axis of its rotor shaft. This can cause problems since the rotor arranged inside a spinnbox has as a rule little freedom of movement.
A section of the spinnbox regularly forms a cover that is movably arranged for opening the spinnbox. In the normal operating state, the rapidly rotating rotor is arranged only a few millimeters from the closed cover. If the previously described movements of the rotor occur in this state there is the danger that the rotor comes to rest with its annular front side on the cover of the spinnbox. Then, significant damage to the particular covers concerned can occur as a consequence of the high rotor speeds of approximately over 150,000 rpm. Furthermore, the rotor that makes contact also suffers and must, if necessary, be replaced after several such events. Both the replacing of a rotor as well as the replacing of a cover is associated with significant cost, which represents a significant disadvantage for the operation of spinning machines.
In order to solve this problem, e.g., DE 44 18 723 C1 teaches that an open-end rotor spinning apparatus can be designed with a spinning rotor comprising an open side limited by a rotor edge, with a housing receiving the spinning rotor and with a rotor cover covering the housing and the open rotor side in such a manner that the area of the rotor cover opposite the rotor edge is designed as a rotor contact surface designed as a wear surface or as a wear-resistant surface. The rotor contact surface suggested by the invention does effectively prevent the rotor from making unintended contact with the cover. However, it proved to be expensive to integrate a closed ring, like the one suggested by the invention, in a closed construction into the cover. This requires further interventions into the geometry of the structural components and results in addition in changes of the spinning behavior of the arrangement.